Since 1991, the Biochemical Physiology (BP) Core has been providing services in two major areas, animal physiology and analytical chemistry. In keeping with the evolving needs of the scientific base and in order to seize on novel scientific opportunities, the applicants have felt the need to modify and expand the services provided by this Core. The implementation of this plan was initiated during the current funding and additions/modifications are presented in this application. Overall, the applicants have enhanced the services provided in this area. They propose to formally divide the two components of the former BP core into two scientific cores: Animal Physiology Core and Analytical Core. During the last ten years, the focus of the animal physiology services has been on surgical preparations, procedures to assess insulin action and glucose tolerance in vivo, and assistance with tracer methodologies. We now propose to increase services in the area of animal physiology to include measurements of energy balance using a comprehensive animal monitoring system (that includes indirect calorimetry) and selective imaging and spectroscopic analyses using Nuclear Magnetic Resonance (NMR).